1 Field of the Invention
The invention relates to a transporting device having a conveyor worm being rotatable about its longitudinal axis, being disposed in a housing having a feed opening and a discharge opening and having a smaller pitch in one partial section of the housing than in a remaining region.
Such transporting devices are known and they are used for various types of substances.
Known transporting devices are frequently only filled to three-quarters of their capacity in order to avoid clogging.
U.S. Pat. No. 3,896,923 discloses a transporting device which includes a conveyor worm having a pitch increasing from the feed opening in the transporting direction. The part of the conveyor worm which transports the most slowly is thus located in the region of the feed opening. At a distance from the feed opening, the pitch of the conveyor worm is larger than in the region of the feed opening. The material being fed-in is thus transported more quickly when it moves away from the feed opening than at the feed opening. As a result, the formation of a stopper is prevented.
Where a transporting device is to be used to convey the material to be transported into a reaction space, it may be a requirement that no air should make its way into the reaction space through the transporting device and/or that no gas should leave the reaction space through the transporting device. A reaction space of that kind can be the low-temperature carbonization drum of a thermal waste disposal plant known from European Patent No. 0 302 310 B1. Waste of different types, e.g. reduced-size domestic rubbish, small-sized industrial waste, but also, in part, solidified slurry, in that case is fed by the transporting device to the low-temperature carbonization drum. The low-temperature carbonization operation in the low-temperature carbonization drum can be disrupted by a sudden increase in the supply of atmospheric oxygen, since the low-temperature carbonization procedure has to proceed sub-stoichiometrically. On the other hand, the low-temperature carbonization gas generated in the low-temperature carbonization device is intended to be fed through a low-temperature carbonization gas pipe to a combustion chamber. No low-temperature carbonization gas must be allowed to flow back through the transporting device and therefore make its way into the environment.
A transporting device through which no gas can flow during operation can be derived from United Kingdom Patent Specification No. 569 370. In that case, the conveyor worm does not extend over the entire length of its housing, so that a stopper is formed out of the transported material. The stopper can prevent any flow of gas in the housing. However, by virtue of the fact that in some sections there is no conveyor worm present, that can result in the transporting device clogging up in such a section.
In order to provide a good transportation of the material, it is necessary that the material to be transported should not stick to the conveyor worm. In order to achieve that, it is customary for rails to be disposed in the housing, on its wall, which protrude into the interspace between the conveyor worm and the housing. Whenever the conveyor worm rotates, material to be transported is stripped from the conveyor worm by the rails. Such rails are subject to high wear and tear.